1. Field
The present disclosure relates generally to launch vehicles and, in particular, to solid propellant launch vehicles. Still more particularly, the present disclosure relates to a method and apparatus for reducing oscillations that may be caused during the generation of thrust by a solid propellant launch vehicle.
2. Background
Launch vehicles are used to transport payloads.
These payloads include, for example, passengers, satellites, shuttles, and other suitable objects. Launch vehicles with solid fuel rockets may be used in lifting the payload. Further, solid fuel rockets also may be used in missiles containing explosive payloads.
One phenomena that may be present with solid rockets is thrust oscillation. This type of oscillation is also referred to as resonant burning. Thrust oscillation is caused by an internal fluid oscillation in pressure. This oscillation is reinforced and amplified by the resonant properties of the combustion chamber. The resonant properties of the combustion chamber are excited by interactions between the combustion chamber shear layer and internal elements of the chamber geometry. Thrust oscillation may shake the entire launch vehicle. Thrust oscillations may occur from vortical structures shed or generated in the solid rocket motor. Acoustic feedback in the flow of gases may result in these oscillations.
Thrust oscillations may be significant. For example, thrust oscillations of up to around 100,000 pounds may occur. Discomfort for passengers, damage to electronic payloads, navigation problems, and/or other issues may occur as a result of these oscillations.
Some solutions have included modifying the geometry of the rocket. This change has included modifications to the length of the rocket, grain configuration, and baffles. Propellant additives have included substances, such as aluminum. The structure modifications include, for example, tuned dampening systems. In some cases, the structural design of the vehicle and payload may be dictated by the loads imposed by thrust oscillations. These types of constraints, however, may be undesirable and may result in increased cost, weight, and/or reduced efficiencies.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possible other issues.